The present invention generally relates to a seat assembly and more particularly, to a seat assembly for use in a motor vehicle which is capable of changing a hardness or resiliency of a seat.
Conventionally, a seat for use in a motor vehicle is commonly settled in hardness by such a mechanical means as springs or the like. In order to obtain a comfortable ride according to a driver's preference, however, there has been proposed a seat assembly which is capable of changing the hardness of the seat by arranging a plurality of air bags within the seat and controlling a pressure of each air bag individually.
For example, Japanese Patent Laid-open Publication Tokkaisho No. 59-230833 discloses the seat assembly for use in the motor vehicle, wherein plural pairs of air bags are arranged in a cushion of a driver's seat and each pair of the air bags is connected to an air supply device through a change-over valve. Furthermore, there is arranged a pressure detecting device in each pair of the air bags. Both of the change-over valves and the pressure detecting devices are connected to a micro-computer which is operable through an operation board. By the above described arrangement, the hardness of the driver's seat can be manually adjusted according to the driver's preference by controlling the change-over valves and the air supply device through the operation board or can be automatically adjusted in compliance with a driver's attitude on the basis of values obtained from the human engineering and previously stored in the micro-computer.
In such seat assembly as mentioned above, however, since the pressures in the air bags are automatically controlled after a change of the driver's attitude has been detected, there has been some delay in controlling the hardness of the seat and as a result, the seat assembly of the above described type can not sufficiently cope with the comfortable ride for the driver.